function startTime() {
    var today = new Date()
    var h = today.getHours()
    var m = today.getMinutes()
    var s = today.getSeconds()
    // add a zero in front of numbers<10
    m = checkTime(m)
    s = checkTime(s)
    document.getElementById('txt').innerHTML = h + ":" + m + ":" + s
    t = setTimeout('startTime()', 500)
}


function checkTime(i) {
    if (i < 10) { i = "0" + i }
    return i
}